[Alex]

From listening to some people talk about it, what seems to be confusing people is:

Spoiler:

They think that Smiley figured out who the mole was and they don't understand how he figured it out, thinking they missed a clue. When really he figured out the ruse and set up a trap to reveal who it was so he learned that at the same we did.

The only problem I had (unless I'm confused and don't realize it) is that I am awful at remembering names and so didn't always know who they were talking about.

I am intrigued enough that I'll probably read the book.